In 1995, Anderson et al. in "Observation of Bose-Einstein Condensation in Dilute Atomic Vapor", Science, Vol. 269, Jul. 14, 1995, pp.198-201, demonstrated that a dilute vapor of .sup.87 Rb could be cooled to the temperature required for observation of Bose-Einstein condensation. Bose-Einstein condensation (BEC) occurs when noninteracting bosonic atoms, below a certain temperature, suddenly develop a macroscopic population in the lowest energy quantum mechanical state of an external confining potential. In such state, the de Broglie wavelength (i.e., Planck's constant divided by the product of mass and the velocity of the speed of light) associated with an atomic wave packet becomes comparable with or larger than the spacing between particles in the gas.
Atoms in this state have coherence properties which are similar to those of optical lasers. Wolfgang Ketterle's group at MIT (i.e., see "Observation of Interference Between Two Bose Condensates", Andrews et al., Science, Vol. 275, Jan. 31, 1997, pp. 637-641), reported observation of interference from two independent Bose condensates. Ketterle's group produced two independent condensates and released the condensates from traps used to create two expanding clouds of atoms--one cloud from one condensate, the other cloud from the other condensate--which eventually overlapped. By taking a picture of the atoms in the overlap region, they observed interference fringes which they interpreted as interference of de Broglie waves originating with each of the two condensates. This was the first demonstration of the phase coherence properties of a BEC and indicated that the output of each condensate was essentially a coherent beam of atoms.
Currently, a number of methods are used to measure the force of gravity and other weak forces. Especially in geological exploration, there exists a need for more highly accurate gravity measurements to provide indications of buried mineral and oil deposits.
Accordingly, it is an object of this invention to provide an improved method for the measurement of weak forces.
It is another object of this invention to provide a method for the measurement of the force of gravity that manifests atomic level measurement accuracies.